Thermal transfer printers have been widely used in modern lives. The common thermal transfer printers include for example faxing machines or the POS (Point of Sale) printers at supermarkets or shops. The configurations of the thermal transfer printers are substantially identical to those of the ordinary printers except for the printing medium and the printing carriers. For example, the ordinary printers supply ink or toner onto papers. Whereas, a thermal transfer printer prints a thermal paper by melting a coating of a ribbon. Generally, for a thermal transfer printer, the ribbon is wound around a ribbon roll, and the thermal paper is wound around a thermal paper roll.
FIG. 1 is a schematic exploded view illustrating a paper supply mechanism of a conventional thermal transfer printer. As shown in FIG. 1, the paper supply mechanism 1 of the conventional thermal transfer printer comprises a first supporting element 11, a second supporting element 12, a first fixing frame 13, a second fixing frame 14 and a first thermal paper roll 15. The first supporting element 11 has a first seam 111. The second supporting element 12 has a second seam 121. The first fixing frame 13 has a first embedding part 131 and a first fixing shaft 132. The second fixing frame 14 has a second embedding part 141 and a second fixing shaft 142. In addition, the first thermal paper roll 15 has a first width W1. A first thermal paper 16 is wound around the first thermal paper roll 15.
A process of installing the first thermal paper roll 15 in the paper supply mechanism 1 will be illustrated as follows. First of all, the first embedding part 131 of the first fixing frame 13 is inserted into a first side of the first thermal paper roll 15, and the second embedding part 141 of the second fixing frame 14 is inserted into a second side of the first thermal paper roll 15. As such, the first fixing frame 13, the second fixing frame 14 and the first thermal paper roll 15 are combined together. Then, the first fixing shaft 132 of the first fixing frame 13 is received in the first seam 111 of the first supporting element 11, and the second fixing shaft 142 of the second fixing frame 14 is received in the second seam 121 of the second supporting element 12. As such, the combination of the first fixing frame 13, the second fixing frame 14 and the first thermal paper roll 15 is installed in the paper supply mechanism 1. Meanwhile, the process of installing the first thermal paper roll 15 in the paper supply mechanism 1 is finished.
The operations of the conventional thermal transfer printer will be illustrated as follows. When the conventional thermal transfer printer is enabled, a thermal print head (TPH) will heat the coating of the ribbon. By heating the ribbon, the originally solid state of coating will be temporarily transformed into the liquid state and transferred to the first thermal paper. The coating is then cooled, and thus the coating is fixed onto the first thermal paper. After the first thermal paper is ejected out of the thermal transfer printer, the thermal transfer printing operation is finished.
Please refer to FIG. 1 again. When the user wants to use a second thermal paper 18 having a second width W2, the combination of the first fixing frame 13, the second fixing frame 14 and the first thermal paper roll 15 needs to be removed from the paper supply mechanism 1. The second thermal paper 18 is wound around a second thermal paper roll 17. By the above method, the second thermal paper roll 17 is then installed in the paper supply mechanism 1. In other words, the conventional thermal transfer printer may print two kinds of thermal papers with different widths by changing the thermal paper rolls.
The conventional thermal transfer printer, however, still has some drawbacks. For example, during operations of the conventional thermal transfer printer, the first thermal paper roll 15 is rotated with respect to the first fixing frame 13 and the second fixing frame 14. After a long use period, the first thermal paper roll 15 and first fixing frame 13 and the second fixing frame 14 will abrade each other. As such, the first embedding part 131 of the first fixing frame 13 and the second embedding part 141 of the second fixing frame 14 fail to be properly fitted with the first thermal paper roll 15. During operations of the conventional thermal transfer printer under this circumstance, the rotation of the first thermal paper roll 15 becomes unstable, and thus the printing quality is deteriorated.
On the other hand, there are many specifications for the inner diameters of the commercially available thermal paper rolls and ribbon rolls. For example, the common specifications for the roll inner diameters are 0.5 inch, 1 inch and 1.5 inch. In addition, the first embedding part 131 of the first fixing frame 13 and the second embedding part 141 of the second fixing frame 14 are only fitted to the dimensions of the first thermal paper roll 15 and the second thermal paper roll 17. In other words, the first fixing frame 13 and the second fixing frame 14 can be applied to no rolls other than the first thermal paper roll 15 and the second thermal paper roll 17. If the inner diameter of the roll is changed, the fixing frame complying with this inner diameter should be used.